Democrats overcome a GOP filibuster with a 60-39 vote in a key procedural move on the $848-billion healthcare legislation. Debate is likely to run through the end of the year.

Reporting from Washington — Without a vote to spare, Democrats pushed their healthcare legislation over its first obstacle on the Senate floor Saturday, as the chamber voted to begin formal debate on a sweeping measure to guarantee medical coverage for nearly all Americans.

The 60-39 vote, backed by all 58 Democrats and two independents, overcame a Republican-led filibuster designed to block consideration of the bill and kept up momentum behind President Obama's top legislative priority.

Although it was only procedural, the dramatic balloting -- before a rare packed gallery on a Saturday night -- also set the stage for a much-anticipated healthcare debate that is expected to begin after Thanksgiving and consume the Senate for the remainder of the year.

"There is an emergency and it exists, and it exists now," Senate Majority Leader Harry Reid (D-Nev.) said just before the vote. "The right response to disagreement is not dismissal. It's discussion. . . . Let us debate our differences."

Democratic congressional leaders, who got a healthcare bill through the House two weeks ago, are laboring to move legislation through the Senate by Christmas so they can deliver on the president's top domestic priority by early next year.

Senate Democrats prevailed Saturday only after Sens. Blanche Lincoln of Arkansas and Mary L. Landrieu of Louisiana announced that they would unite with their party. The two centrists from traditionally Republican states had been withholding their support for the procedural vote.

"It is more important that we begin this debate to improve our nation's healthcare system for all Americans, rather than just simply drop the issue and walk away," Lincoln said.

Not a single Republican backed the motion to proceed with the bill, which GOP lawmakers declared would pave the way for a government takeover of healthcare and drive up the national debt. Sen. George V. Voinovich (R-Ohio) missed the vote.

"We know that Americans oppose this bill," Senate Minority Leader Mitch McConnell (R-Ky.) said as debate got underway. "They certainly don't think it's what we need at a time when . . . one out of 10 working Americans is looking for a job."

The $848-billion measure that will now be laid before the full Senate is designed to expand coverage to an additional 31 million Americans over the next decade, while still restraining federal deficits and making the healthcare system more efficient and reliable for patients.

The centerpiece of the Senate bill is a series of regulations requiring insurers to offer coverage to all Americans, regardless of their health status, and to create government-regulated insurance exchanges in which people who do not get covered through their jobs would be able to shop for plans.

Reid has proposed funding the measure with a politically delicate mix of cuts to the federal Medicare system and new taxes on parts of the healthcare industry, high-end "Cadillac" health plans and wealthy households.

Reid's 2,074-page proposal almost certainly will undergo changes as Democrats and Republicans offer amendments challenging aspects of the legislation.

Saturday's debate provided a preview of fights to come.

Landrieu, who has voiced deep reservations about Reid's proposal to create a new government insurance plan, the so-called "public option," said she would push for larger tax credits to help small businesses provide health benefits to their workers.

"There is a great deal more work that needs to be done," Landrieu said, warning that her vote Saturday did not mean she would support the final package.

Lincoln, who faces a tough reelection fight next year, explicitly said she would not back further procedural votes on the bill in its current form.

"I am opposed to a new government-administered healthcare plan as part of comprehensive health insurance reform," Lincoln said. "While cost projections show that it may reduce costs somewhat, those projections don't take into account who pays if it fails to live up to expectations."

Reid has tried for months to balance the competing demands of his diverse caucus, which includes a socialist as well as lawmakers from states that have not voted for a Democratic presidential candidate in nearly 50 years.

Liberal lawmakers have already warned that they will not brook any moves to further weaken the government insurance plan in Reid's bill, which the nonpartisan Congressional Budget Office has estimated would provide coverage to 3 million or 4 million people.

And Friday, the liberal grass-roots powerhouse MoveOn.org began running television ads in Arkansas and Maine attacking an alternative favored by some centrists that would trigger the creation of a government plan only in parts of the country where commercial insurers fail to meet benchmarks for affordability and quality.

A leading champion of the "trigger" approach is Maine Sen. Olympia J. Snowe, a moderate Republican who Democratic leaders still hope will back the final healthcare package.